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2005 330i manual transmission performance package
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OP, inexplicable coolant loss and engine running hot could be a bad sign.

Do repeat the pressure test, and if you still can't find an external leak, remove the spark plugs and look inside the cylinders.
Visually inspecting the oil isn't a good way to make sure it isn't contaminated with coolant - ask me how I know.
 

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2002 330Ci
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I've run into bleeding issues before that resulted in problems until the system was bleed cleanly but they wouldn't have resulted in the problems you seem to be experiencing. Since your system doesn't seem to be holding pressure you need to find out why it's leaking. I have a water pump fail a couple of months after install with a genuine part. It was seeping from the weep hole. I didn't run a pressure test so cannot tell you if it would have showed up but I bet it would have.
 

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Discussion Starter · #23 ·
No need to drain. Read through this bleeding to understand it, then give it a try.
Post #13 of this thread:
I followed your instructions closely with no change. No heat and I shut the car off once I saw the temp gauge hit 110.

Ill get my hands on my leak down kit and try that next.

Thanks for everyone’s help so far
 

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Discussion Starter · #24 ·
Wow, just got out the car after my test and discovered some new delicious coolant on the ground. It’s not a constant leak but it’s a decent bit of it.

Did maybe my radiator pop? It’s coming from the drivers side near the expansion tank, but there’s drips of fluid all over the place under the car. It’s on the sway bar, the expansion tank has stuff all over the side. Cant quite narrow it down.

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Thus, I think eliminating the circulating air before driving the car isn't worth my time -
What?
The cooling system is sort of self-bleeding - the air bubbles trapped inside circulate with the flow while the engine is running and eventually get trapped inside the expansion tank.
So before the air pockets eventually are trapped in the tank, how did you drive to places without overheating the air head, or just let it resting in the garage?
It is more important to look for leaks and to pay attention to the engine temperature.
So no bleeding air is needed, and then when the temp gauge moving toward the red zone, then shut it off and pray the GOD?
 

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2005 330i manual transmission performance package
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What?

So before the air pockets eventually are trapped in the tank, how did you drive to places without overheating the air head, or just let it resting in the garage?

So no bleeding air is needed, and then when the temp gauge moving toward the red zone, then shut it off and pray the GOD?
Too many assumptions here.
I fill up the cooling system as per TIS, while the front of the car is raised.
Check for obvious leaks.
Start the engine and don't bother opening the bleed screw again as some do.
Check for obvious leaks.
Drive the car a few times around the block, keeping an eye on the engine temp.
Chech for obvious leaks.
Drive the car until the engine is at operating temp, make sure the system behaves and temp doesn't go above 98-99C.
Park the car overnight.
Check for leaks on the next day, check the coolant level, top off if needed (usually less than 200 ml / 7 Oz).
Eventually check the coolant again a few weeks after, but almost never need to add more coolant.
 

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2005 330xi Auto, 2006 330ci Vert Auto
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Hi all,

I'm running around trying to diagnose my e46 325i touring manual with an overheating and disappearing coolant issue. Car has 205,000 miles.

In 2019 around 180,000 miles, I replaced the entire cooling system (hoses, sensors, thermostat, water pump, expansion tank, etc), bar the radiator. Everything was OE or OEM replacement. Car has been super solid since.

Recently at my oil change, the guys said coolant was low but they didn't have any more.
The next day I get some drive through food and pull out hard, revving to like 6k. I look down a mile or two later and my temp gauge is in the red. It was dark and raining so I finished the quarter/half mile back home and turned it off right away.

I've always vigilantly watched the gauge and never seen it move past dead center. I know I was supposed to pull over immediately, and I did so as soon as I could safely.

I refilled coolant and drive a few miles the next day and it overheated again. This time, I shut it off again as soon as I could. It hit the red and I got it towed home.

So, things I've done/noticed:
  • Coolant refilled and system bled multiple times.
  • Rented a cooling pressure test kit and it held 9psi no problem. No audible leaks or bubbles spotted.
  • Unplugged lower radiator fan switch to trigger fan to be on full and it didn't help - still climbed past 110 Celsius
  • No coolant in oil (recent oil change was 2 days before first overheat)
  • Car will idle in the driveway for 20+ mins but eventually start to overheat. If I drive it, it'll overheat in like a mile or less.
  • Seemingly no heat coming out even when engine is warm
  • Noticed light white smoke coming from exhaust at idle and when revving, even when warm. Filmed a video of that here. It's hard to see, but you'll notice it for sure. E46 overheating and white smoke
My logical next steps I think are replace water pump and/or thermostat again, but I'm concerned by the white smoke.

Do I have a cracked head?
Sounds like your car was working fine from 2019 until a few days ago. I'm going to assume that prior to what you just described, you did not have overheating problems or lack of cabin heat (do let us know if this is not true). If that's the case, it's not a case of bad bleeding because if it was bad bleeding, then you would've noticed all sorts of problems over the last 3 years. The fact that your cooling system can only hold 9 psi and now you have a pool of coolant on the ground, something broke and you're the best person to go find what broke. While we're on this subject, Bentley manual spec's 1.5 bar as the test pressure for the radiator and the common BMW expansion tank cap is rated at 2 bar. As such, we can speculate that the cooling system pressure when hot is approx. 1-1.5 bar. Keep this in mind when you're pressure testing. 1.5 bar = ~ 21 psi so the previously suggested 18 psi test is right on target. Unfortunately your cooling system did not hold that pressure for long......

Wow, just got out the car after my test and discovered some new delicious coolant on the ground. It’s not a constant leak but it’s a decent bit of it.

Did maybe my radiator pop? It’s coming from the drivers side near the expansion tank, but there’s drips of fluid all over the place under the car. It’s on the sway bar, the expansion tank has stuff all over the side. Cant quite narrow it down.
Based on this description, I would concentrate your investigation on the radiator and the hard coolant pipes under the intake manifold.
 

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Too many assumptions here.
I fill up the cooling system as per TIS, while the front of the car is raised.
Check for obvious leaks.
Start the engine and don't bother opening the bleed screw again as some do.
Check for obvious leaks.
Drive the car a few times around the block, keeping an eye on the engine temp.
Chech for obvious leaks.
Drive the car until the engine is at operating temp, make sure the system behaves and temp doesn't go above 98-99C.
Park the car overnight.
Check for leaks on the next day, check the coolant level, top off if needed (usually less than 200 ml / 7 Oz).
Eventually check the coolant again a few weeks after, but almost never need to add more coolant.
Good for you, but there are some people had no luck and continued to have overheating and no cabin heat after doing this way.
 

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2005 330i manual transmission performance package
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Good for you, but there are some people had no luck and continued to have overheating and no cabin heat after doing this way.
Sorry to hear but can't stress enough the importance of two things - front of the car raised; coolant mix poured in slowly.

If you get into a situation where there is too much air somewhere inside the cooling passages, enough to obstruct the flow rather than move alongside the coolant, opening the bleeder screw while the engine is idling isn't likely to help dislodge it.
What may help is driving the car - acceleration/deceleration, going through bumps, revving the engine higher than at idle...
 

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What may help is driving the car - acceleration/deceleration, going through bumps, revving the engine higher than at idle...
They started doing this but the gauge moving toward the red zone, then what?
My method is not much different with the TIS instruction, except I don't want to do the extra step using turkey baster to remove excess coolant out after closing the bleeder.
 

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They started doing this but the gauge moving toward the red zone, then what?
My method is not much different with the TIS instruction, except I don't want to do the extra step using turkey baster to remove excess coolant out after closing the bleeder.
Well, if the temp starts going higher than normal operating range, at least you are in the in the driver seat where you are in position to notice and shut the engine off promptly, not by the engine bay, looking for air bubbles coming out of the bleeder screw...
 

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2002 330i auto
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Good for you, but there are some people had no luck and continued to have overheating and no cabin heat after doing this way.
If temperature is out of the blue and there is no cabin heat, you know something is wrong. Who continues after observing no cabin heat?

So why does filling coolant go wrong for so many? I have never had trouble, never jacked the front of the car, never dumped half a gallon of coolant on the ground "bleeding". Even side of the road repairs (both were E36, 1 blown ET and one radiator neck). I just did a water pump, put everything I drained back in, ran it for maybe a minute, called it done. Topped off in the morning.

What is the actual cause of these problems? My guess is rushing the fill entraining a lot of air, not waiting for air to come out, or sticky heater valves/blocked cores. What else could it be?
 

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What is the actual cause of these problems? My guess is rushing the fill entraining a lot of air, not waiting for air to come out, or sticky heater valves/blocked cores. What else could it be?
I think there is trapped air still in the head when filling up the tank until no bubbles flow out the bleeder. AFter the bleeder was closed, the trapped air could not escape during driving.
With my method, with engine running and coolant flowing through the head and flushing out the air, and with the bleeder crack-opened for air to escape until none, then close. This ENSURE no air in the head nor around the WP.
 

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Discussion Starter · #39 ·
Ok, got a bit more info to add here. I think I've narrowed it down to head gasket or cracked head.

Pulled the plugs and this is what they looked like. All plugs and coil packs were replaced less than 2,000 miles ago in September.
It's cyl 1 from left to cyl 6 on right.
Note the cylinder 3 plug is a lot cleaner looking.

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I ran a leak down test today and most cylinders have a little bit of air leaking from the oil cap.
Cylinder 2 leaks a ton of air into cylinder 3. My gauge isn't reading properly, so I don't know percentage but it is very audibly leaking and you can feel it clearly.
I double, triple checked I was on the correct stroke.

This is why I think the condition of spark plug 3 is noteworthy. Is the head gasket bad between those cylinders there and there's mixing between the two cylinders?

The other thing I failed to mention in the original post as it didn't seem relevant at the time was that I had a misfire code a few months ago.
It was in late September and it was resolved by replacing all the coil packs and spark plugs. (done less than 2000 miles ago as previously mentioned).

Was this possibly related or just coincidence?
 

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2000 323i
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As you know these engines don't take an overheat, even a brief one , very well.

you greatly increased the risk of a head gasket /warped head b driving your car the quarter to half mile home while in the red...

Before you replace any parts you need to test for head failure AND find the source of your leak.. BTW - a pressure test at 9psi does nothing...the M54 cooling system runs at 18-20psi...

I would do the following:
  • compression test
  • swab each cylinder for coolant...run the car up to temp, shut it off let it sit overnight, pull plugs and swab each cylinder
  • Maybe get a UV coolant test kit - dye, UV light, glasses - you might be able to borrow at Autozone.

Right now, I think you have an air pocket in the cooling system..keep bleeding...then do the steps above..
I'm with EffDuration on this - you might have a warped cylinder head or a blown head gasket.

You mentioned a mysterious coolant leak, seeing your temperature gauge go to red, seeing white smoke from the exhaust, yet you replaced the cooling system.

That probably means that in your engine block, your head gasket has a leak somewhere. If you see white smoke in your exhaust, that means your coolant is getting into one of your cylinders and is being burnt, which then gets piped out thru your exhaust. If you are losing coolant, that means that the coolant is leaking somewhere and since you replaced almost all the parts of the cooling system, the one place that can leak coolant is the engine block.

I had the same symptoms on my other car (not a BMW). White smoke in the exhaust, temperature gauge spiked to red while driving. It was a blown head gasket.

You're going to need to do a compression test on the cylinders as EffDuration recommended.
 
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